Lexical Analysis · Compiler Design · GATE CSE

A lexical analyzer uses the following token definitions

• letter → [A - Za - z]

• digit → [0-9]

• id → letter (letter $\mid$ digit)*

• number → digit $^{+}$

• ws → (blank | tab | newline) ${ }^{+}$

For the string given below,

$x1 \quad 23mm \quad 78\quad$ y $\quad7 z \quad z z 5 \quad 14 A \quad 8 H \quad A a Y c D$

the number of tokens (excluding ws) that will be produced by the lexical analyzer is

$\_\_\_\_$ . (answer in integer)

Consider the following C statements:

char str1 = "Hello; / Statement S1 */

char str2 = "Hello;"; / Statement S2 */

int str3 = "Hello"; / Statement S3 */

Which of the following options is/are correct?

Consider the following two sets:

Set X

P. Lexical Analyzer

Q. Syntax Analyzer

R. Intermediate Code Generator

S. Code Optimizer

Set Y

1. Abstract Syntax Tree

2. Token

3. Parse Tree

4. Constant Folding

Which one of the following options is the correct match from Set X to Set Y?

Group 1

Group 2

printf("i = %d, &i = %x",i, &i);

I. begin
II. program
III. <>

List - I

List - II

Consider the following C code segment:

a = b + c;

e = a + 1;

d = b + c;

f = d + 1;

g = e + f;

In a compiler, this code segment is represented internally as a directed acyclic graph (DAG). The number of nodes of nodes in the DAG is ______

$$\eqalign{ & {T_1}:\,\,\,a?{\left( {b|c} \right)^ * }a \cr & {T_2}:\,\,\,b?{\left( {a|c} \right)^ * }b \cr & {T_3}:\,\,\,c?{\left( {b|a} \right)^ * }c \cr} $$

Note that $$'x?'$$ means $$0$$ or $$1$$ occurrence of the symbol $$x.$$ Note also that the analyzer outputs the token that matches the longest possible prefix.

If the string $$bbaacabc$$ is processed by the analyzer, which one of the following is the sequence of tokens it outputs?

I. A programming language which does not permit global variables of any kind and has no nesting of procedures/functions, but permits recursion can be implemented with static storage allocation

II. Multi-level access link (or display) arrangement is needed to arrange activation records only if the programming language being implemented has nesting of procedures/functions

III. Recursion in programming languages cannot be implemented with dynamic storage allocation

IV. Nesting procedures/functions and recursion require a dynamic heap allocation scheme and cannot be implemented with a stack-based allocation scheme for activation records

V. Programming languages which permit a function to return a function as its result cannot be implemented with a stack-based storage allocation scheme for activation records